Atheism and vegetarianism

As we all evolved from common ancestors, and atheists reject the idea that we have god given dominion over the other animals, what ethical justification is there for not considering then suffering of other species?

It seems that to discriminate on the grounds of species is just as arbitrary as to discriminate on the basis of skin colour, sex etc.

I base my ethics on minimising unnecessary suffering and death and promoting well being and happiness. What are others ethics based upon?

The United States Department of Agriculture confirmed today that the nation's fourth case of bovine spongiform encephalopathy (BSE), sometimes referred to as "mad cow disease" was found in a dairy cow in California. The animal has been euthanized and the carcass is being being held under State authority at a rendering facility in California and will be destroyed.

This article says that these cows did not contract BSE from food. Where else could they have gotten it? I think the corporations probably went back to their dirty habit of feeding ground up cows and sheep to cows in their food.

More meat! More meat! You'll go from not wanting to think about what it is, to not being able to think at all.

Without god we need to find our own morals. Evolution tells us we are just another species. In common with other species, we suffer. Causing unnecessary suffering or harm is wrong. Eating meat involves causing harm and suffering. Eating meat is not essential for survival, therefore it is unnecessary. Therefore, to eat meat is immoral.